1. Field of the Invention
The invention relates to processor technologies. In particular, the invention relates to a processor for controlling performance in accordance with a chip temperature, and a method of controlling a processor.
2. Description of the Related Art
With increasing trends toward finer manufacturing processes and higher device integration, it has become extremely important for LSI design to take the amount of heat generation into account as chips' performance limits. At higher temperatures, chips can malfunction or drop in long-term reliability. Various measures against heat generation have thus been taken. For example, in one of the measures, radiating fins are formed on the top of a chip so as to release heat occurring from the chip.
Besides, it has been studied to schedule tasks of a processor based on the distribution of power consumption of the chip (for example, see US Patent Application Publication No. 2002/0065049).
In cases of a sharp rise in temperature or the like, the foregoing measures may sometimes fail to address sufficiently. One of the possible techniques for dealing with those cases is to decrease the performance itself by such processing as lowering the operating frequency of the chip. Decreasing the performance is wasteful, however, if more than necessary.